Review on the Linear Accelerators with Flattening - myassignmenthelp

Question: Discuss about theReview on the Linear Accelerators with Flattening. Answer: A review on the linear accelerators with flattening filter in the administration of radiation therapy Introduction The linear accelerators with flattening filter free beam capabilities are now gaining traction in the radiation therapy arena. There are standard methodologies that have been used to administer the radiation therapy. In this brief report, a special focus is on the FFF beams where they are assessed by comparing their dosimetric characteristics with the conventional FF beams. In other words, what special features does the FFF beam have that makes them unique in the radiation therapy administration. Xiao1 asserts that the FFF are used to absorb radiations so as to direct it to the spots where cancerous cells can be annihilated. The photons are absorbed, scattered or produced in an ordered fashion. Therefore, the flattening filters act as attenuators, hardeners and scatters in the beam path2. The Flattening Filters The FFF has been in use in the past due to its facilitation of the delivery time so that what took so long to deliver the treatment (for SRS) was considerably shortened by the method. However, concerns have been raised on its efficiency as sometimes it leaves behind traces of radiation that can further cause other cancer types1. The differences in dosimetry properties The total dose rate for FFF is 2.46 times higher than the FF beams. Ultimately, the dose rate increase facilitates elimination of a larger portion of photons from the main beam center. Connectedly, treatment delivery efficiency has also been improved courtesy of the higher dose rates registered in FFF beams3. The surface dose of FFF beams are at a higher level compared with FF beams1. This is mainly attributed to the increased incident contaminant charged particle and low energy photons being propagated. On the side of the scatter factor, the FF beams are mainly attributed to the dispersion that is often exhibited when streamed3. The FFF beams tend to be denser at their penumbra hence recording relatively lower scatter factors. Therefore, in treating cancer, it even gets better with the use of FFF beams. The beam profiles of FFF and FF also show a marked difference. The FFF beams have relatively smaller penumbra width than FF beams; this is mainly due to softer beam spectrum. Clinical Applications FFF beams were initially developed and used in the treatment of the SRS (small field stereotactic radiosurgery). Later, their use has been extended to areas such as annihilation of brain tumors4. On target coverage, the FFF beams capture a larger portion of the target unlike FF beams. Besides, the time taken to complete treatment has greatly been improved with the use of FFF beams. Limitation Of The Fff Beams The beam often experiences a phenomenon technically referred to as photon target burn-up. Problems of modulation has also arisen especially since it is the target is distance-dependent and sometimes off-axis modulation may result into missing of the target hence can be another source for additional unsolicited radiations. Conclusion The review above ostensibly discussed about the FFF beams. Furthermore, comparison with other conventional beams has been done. The focus was on how the mentioned beams differ with the normal radiation beams hence the difference in dosimetry and other relevant properties have been relooked. Certainly, as mentioned earlier, the future of these beams in the radiation therapy administration is still bright. However, a number of issues must be fixed such as the radiation safety during administration of the therapy; for instance, are there residual radiation after administration? Besides, the modulation and propagation challenges cited must be addressed in a continuous fashion. References Xiao Y. Flattening filter-free accelerators: a report from the AAPM Therapy Emerging Technology Assessment Work Group. 2015; pp 2-3. Available from: https://onlinelibrary.wiley.com/doi/10.1120/jacmp.v16i3.5219/pdf Sunil Dutt Sharma. Unflattened photon beams from the standard flattening filter free accelerators for radiotherapy: Advantages, limitations and challenges. Journal of Medical Physics. 2011. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3159217/ Simon Duane. Dosimetry for Flattening Filter Free (FFF) linac beams and small fields (SF). National Physics laboratory. 2013. Available from: https://www.npl.co.uk/upload/pdf/20131202-duane.pdf MatthiasKretschmer et al. The impact of flattening-filter-free beam technology on 3D conformal RT. 2013. Available from: https://ro-journal.biomedcentral.com/articles/10.1186/1748-717X-8-133